Significant Accounting Policies - Foreign Currency Translation (Details) VEF in Billions	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2017 VEF
Foreign Currency Translation
Operating income of Venezuelan subsidiary as percent of consolidated amount high end of range	1.00%
Maximum balance of company's net monetary assets in Venezuelan bolivars		VEF 5
Exchange rate established by Venezuelan government from bolivars to dollars - DIPRO		10
Exchange rate established by Venezuelan government from bolivars to dollars - DICOM		2,600